Magnetic Properties of Fe2GeMo3N; an Experimental and Computational Study

A polycrystalline sample of Fe2GeMo3N has been synthesized by the reductive nitridation of a mixture
of binary oxides in a flow of 10% dihydrogen in dinitrogen. The reaction product has been studied by
magnetometry, neutron diffraction and M€ossbauer spectroscopy over the temperature range 1.8 #
T/K # 700. The electronic properties have been modelled by DFT and Monte Carlo methods.
Fe2GeMo3N adopts the cubic h-carbide structure with a ¼ 11.1630(1) at 300 K. The electrical
conductivity was found to be 0.9 mU cm over the temperature range 80 # T/K # 300. On cooling
below 455 K the compound undergoes a transition to an antiferromagnetic state. The magnetic unit cell
contains an antiferromagnetic arrangement of eight ferromagnetic Fe4 tetrahedra; the ordered atomic
magnetic moments, 1.90(4) mB per Fe atom at 1.8 K, align along a <111> direction. DFT predicts an
ordered moment of 1.831 mB per Fe, albeit with a N eel temperature of >549 K. Monte Carlo
calculations confirm that the experimentally determined magnetic structure is the lowest-energy
antiferromagnetic structure. These results emphasise the potential of these computational methods in
the search for new magnetic materials.